Fertilizer and making same



Patented Jan. 15, 1946 UNITED STATES PATENT oFncE No Drawing.Application April 7, 1943, Serial No. 482,147 v 7 Claims.

This invention relates to fertilizers and to the process of producingthe same, more particularly to a micro-organic vitamin-rich fertilizerwhich includes in its composition yeast and lignin, and has for anobject the provision of improvements in this art. This application is acontinuationin-part of my copending application, Serial No. 382,979,filed March 12, 1941.

The fertilizer may be and preferably is made from the waste liquor fromthe sulphite pulp process. This material is plentiful and normally anobjectionable, acid refuse which is diflicult to dispose of and pollutesthe streams into which it usually is discharged. Some efforts have beenmade to put the material to economic use and certain small amounts areused for the production of baker's yeast, but the total requirements ofall known uses scarcely touch the supply. Yeast propagation in theneutralized liquor is possible because of its sugar content. The liquoralso has considerable lignin content which, however, is a disadvantagein normal yeast manufacture and every care is taken to insure that it isnot con tained in the final product.

One yeast production process, using sulphite waste liquor, which hasbeen successful is known as the Heijkenskjold process and is describedin one form in the patent to Heijkenskjold, Number 1,881,557. In thisprocess the yeast growth is started in a sugar solution to whichneutralized waste sulphite liquor is gradually added and also yeastnutrient salts with accompanying intense aeration which reduces to aminimum the formation of alcohol and counteracts the toxic effect of thelignin on the yeast fungi. Other yeast nutrient salts are added inexcess of the amount required for fungi growth. After the yeastpropagation process is terminated the yeast is carefully freed from thelignin and the non-assimilated yeast nutrient salts by repeatedseparations and washings.

Bakers yeast consists of a particular race of fungus, Saccharomycesceriviseae, and utilizes only certain varieties of the sugars containedin sulphite liquor. The other sugars as well as the non-assimilableexcess of yeast nutrient salts and the lignin are hence wasted in theproduction of bakers yeast from waste sulphite liquor.

According to the present process it is possible to propagate variousraces of yeast because a number are suitable for fertilizer which wouldhave no value for bakers uses; hence it is possible to utilizepractically all of the sugars contained in the waste sulphite liquor. Inaddition, the

non-assimilated yeast nutrient salts and the substantially nil becauseof the prohibitive cost of propagating it by usual methods. Moreover,when used alone and unless specially protected its full value is notrealized because under certain common conditions it tends todisintegrate and disappears from the soil with greatly reduced benefitto the plants. v So; although the Heijkenskjold process provides amoreinexpensive yeast, so far as known there has been no previous attempt touse it as a fertilizer, and particularly no attempt to combineprotective and balancing substances with it to make it fully availableas required by growing plants. Such utilization is provided by thepresent process.

In the practice of the present process the yeast is combined withlignin. Lignin itself has valuable properties' as a soil improver, onebeing its highly hygroscopic nature enabling it to absorb water andplant nutrients. Another is that lignin is almost impervious todecomposition by micro-organisms and its soil improving properties aretherefore of long duration.

The complete fertilizer may be produced from sulphite waste liquor by avariation of the.

Heijkenskjold process and it has the advantage over that process in thatit preferably employs various races of yeast instead of'one and thusutilizes practically all of the sugars contained in the sulphite wasteliquor. The Heijkenskjold process may be followed closely in the initialstages up to the propagation of the yeast so there is no need todescribe it at length, reference being made to the aforementionedHeijkenskjold patent. However, it is to be noted that even in this knownprocess a variation is introduced in that different races of yeast arepreferably employed instead of the one which is useful for bakingpurposes, andthat these other races may be hardier and easier topropagate under the adverse conditions which necessarily exist at bestin connection with yeast propagation in sulphite waste liquor. At thestage before the Heijkenskjold process is concluded the present processdeparts completely. Instead of washing away the lignin and thenon-assimilated yeast nutrient salts as'is absolutely necessary for theutilization of the yeast for baking, these normally undesired wasteproducts are retained with the yeast, the excess water only beingeliminated by dehydrat ing the entire yeast mesh in one of a-number ofknown ways.

The dehydration or drying step is preferably carried out in such manneras to prevent any substantial destruction of the yeast vitamins and topreserve an appreciable part of the yeast in a live though dormantstate. The temperature of the drying is about 200 degrees F. with somepermissible variations depending on the time and method of drying. Forexample, in order to preserve a maximum amount of vitamins and liveyeast cells it may be economical to increase the time and cost of thedrying procedure by lowerin the temperature at certain stages toapproximately 140 degrees F.

In the product so produced the maximum value of the yeast can be madeavailable to the plants, and moreover the desirable properties of thelignin and the non-assimilated yeast nutrient salts are also realized.These salts, mainly compounds of nitrogen and phosphorus. are valuabledirectly as plant fertilizer and are commonly used as such. i

In combination with yeast, lignin thus has two important functions:

1. The lignin forms a protective coating around the yeast cells whichhas the effect of furnishing them protection from disintegration unlessthere is sufficient moisture in the soil to penetrate the lignincoating. This is important be cause without such moisture there can beno utilization of the yeast components by the plants any way. Forinstance, unprotected yeast would under dry soil conditions, notably onthe surface of the soil, disintegrate rapidly withvery much reducedbenefit to the plants; whereas with the protective water-soluble lignincoating the yeast cells will be protected until moisture conditions aresuch that the yeast components can be utilized by the soil bacteria andthen assimilated by the plants, At such time and no sooner will thelignin coating be penetrated and the yeast cells exposed. 1

2. Lignin also has the function of absorbing and storing nutrientsreleased by the disintegration of the yeast cells, in the same manner asthe lignin will absorb the non-assimilated yeast nutrients of thepropagation mash. In this manner lignin acts as a balancer between thesupply and demand of nutrients released by the disintegration of theyeast.

In order to serve the first purp se, only very small quantities oflignin would be required. To serve both purposes it is desirable to haveconsiderable excess of lignin combined with the yeast. Lignin will forinstance absorb and retain as much as 14% of its own weight in potash.Assuming that lignin has approximately the same capacity with respect toother fertilizer salts, I propose to have present from five to ten timesas much lignin as yeast, figured on dry substance, which figures mightbe varied for difierent soil conditions as for example whether rich orpoor in humus. If yeast and lignin were used in the proportionsobtainable on the average in a normal sulphite liquor yeast propagationwort, such proportions can be made to vary from five to ten parts ligninto one part of yeast, depending on the races of yeast and conduct of thepropagation, thus agreeing with the suggested proportions.

As a specific example of the process, the sulphite'waste liquor isneutralized, and, avigorous yeast culture having been started in a sugarsolution, the prepared liquor is added. to the growing yeast, with theaddition of excess amounts of yeast nutrient salts and with intenseaeration of the wort, all as more fully set forth in the Heijkenskjoldpatent. Difierent races of yeast may be used in addition or asalternative to the particular species useful for baking according to thepatent. The resultant final yeast mash is then dehydrated and theproduct may in this state be kept indefinitely.

This product can be used alone as a fertilizer and soi1 improver or itcan be mixed with other fertilizer components to act with them andincrease their efliciency.

It is thus seen that the method provides a new and very valuablemicro-organic vitamin-bearing fertilizer and one which can beinexpensively produced from a normally objectionable waste product. Alsothat by the preferred method a number of hardy yeast races arepropagated to utilize a maximum of the sugar content of the sulphitewaste liquor with correspondingly higher yields of yeast and simplifiedpropagation process.

While the method has been particularly described in connection with theproduction of fertilizer from sulphite waste liquor because thisprovides a bountiful source of raw material at practically no cost, thusmaking the product sufficiently cheap for general use, it is to beunderstood that yeast and lignin and such other ingredients as aredesired in the fertilizer may be obtained from other sources wheneverfeasible.

It is to be noted that an advantage of the process is the ability of thelignin to absorb the excess of nutrient salts which are not assimilatedin the yeast propagation. Also it provides a fertilizer which willremain available for long periods of time, the lignin reducing the lossfrom the soil of the other components through excessive dryness ormoisture. By dehydration of the whole yeast mash without the separationof the yeast from the mash, all the valuable fertilizing contents of thenon-assimilated yeast nutrient salts as well as of the yeast and thelignin are retained in the final product.

While one embodiment of the invention has been described for purposes ofillustration, it is to be understood that the invention may have variousembodiments within the limits of the prior art and the scope of thesubjoined claims.

I claim as my invention:

1. The process of preparing a hygroscopic fertilizer from sulphite wasteliquor containing lignin in solution which comprises, producing yeastfrom the liquor by fermentation accompanied by vigorous aeration whileadding yeast nutrient salts in excess of the amount required by theyeast, and

maintaining the lignin in solution, said yeast being substantially freefrom alcohol, and drying the whole mash at a temperature suflicientlylow to preserve vitamins and live yeast in admixture with thewater-soluble lignin and nutrient salts in the wort as a completeprotective coating on the yeast cells.

2. The process of preparing a hygroscopic fertilizer from sulphite wasteliquor containing lignin in solution which comprises, producing yeastfrom the liquor by fermentation accompanied by intense aeration, andmaintaining the lignin in solution, said yeast being substantially freefrom alcohol, and drying the whole mash at a temperature sufficientlylow to preserve live yeast in admixture with the water-soluble lignin inthe wort as a complete protective coating on the yeast cells.

3. The process as set forth in claim 2 wherein the dehydration procedureis conducted at a temperature of not higher than 200 degrees F. to avoidagglutinization of the yeast while preserving some live yeast in thedormant state and preserving considerable amounts of the vitamincontent.

4. A hygroscopic fertilizer composed of the whole dried residue ofsulphite waste liquor yeast propagation mash including yeast, which issubstantially free from alcohol, together with watersoluble lignin andyeast nutrient salts as a. complete protective coating on the yeastcells.

5. A hygroscopic fertilizer composed of the dried residue of sulphitewaste liquor yeast propagation mash including yeast, substantially freefrom al-

